#include <bits/stdc++.h>
using namespace std;

#define REP(i,n) for(ll i=0;i<(ll)n;i++)
#define dump(x)  cerr << "Line " << __LINE__ << ": " <<  #x << " = " << (x) << "\n";
#define spa << " " <<
#define fi first
#define se second
#define ALL(a)  (a).begin(),(a).end()
#define ALLR(a)  (a).rbegin(),(a).rend()

using ld = long double;
using ll = long long;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pdd = pair<ld, ld>;

template<typename T> using V = vector<T>;
template<typename T> using P = pair<T, T>;
template<typename T> vector<T> make_vec(size_t n, T a) { return vector<T>(n, a); }
template<typename... Ts> auto make_vec(size_t n, Ts... ts) { return vector<decltype(make_vec(ts...))>(n, make_vec(ts...)); }
template<class S, class T> ostream& operator << (ostream& os, const pair<S, T> v){os << "(" << v.first << ", " << v.second << ")"; return os;}
template<typename T> ostream& operator<<(ostream &os, const vector<T> &v) { for (auto &e : v) os << e << ' '; return os; }
template<class T> ostream& operator<<(ostream& os, const vector<vector<T>> &v){ for(auto &e : v){os << e << "\n";} return os;}
struct fast_ios { fast_ios(){ cin.tie(nullptr); ios::sync_with_stdio(false); cout << fixed << setprecision(3); }; } fast_ios_;

template <class T> void UNIQUE(vector<T> &x) {sort(ALL(x));x.erase(unique(ALL(x)), x.end());}
template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }
void fail() { cout << -1 << '\n'; exit(0); }
inline int popcount(const int x) { return __builtin_popcount(x); }
inline int popcount(const ll x) { return __builtin_popcountll(x); }
template<typename T> void debug(vector<vector<T>>&v,ll h,ll w){for(ll i=0;i<h;i++)
{cerr<<v[i][0];for(ll j=1;j<w;j++)cerr spa v[i][j];cerr<<"\n";}};
template<typename T> void debug(vector<T>&v,ll n){if(n!=0)cerr<<v[0];
for(ll i=1;i<n;i++)cerr spa v[i];
cerr<<"\n";};

const ll INF = (1ll<<62);
// const ld EPS   = 1e-10;
// const ld PI    = acos(-1.0);
// const ll mod = (int)1e9 + 7;
const ll mod = 998244353;

template <std::uint_fast64_t Modulus> class modint {
  // long long から modint を作るときは必ず正の数にしてからコンストラクタに入れること！ 
  // そうしないとバグります
  using u64 = std::uint_fast64_t;

public:
  u64 a;

  constexpr modint(const u64 x = 0) noexcept : a(x % Modulus) {}
  constexpr u64 &value() noexcept { return a; }
  constexpr const u64 &value() const noexcept { return a; }
  constexpr modint operator+(const modint rhs) const noexcept {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint rhs) const noexcept {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint rhs) const noexcept {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint rhs) const noexcept {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint rhs) noexcept {
    a += rhs.a;
    if (a >= Modulus) {
      a -= Modulus;
    }
    return *this;
  }
  constexpr modint &operator-=(const modint rhs) noexcept {
    if (a < rhs.a) {
      a += Modulus;
    }
    a -= rhs.a;
    return *this;
  }
  constexpr modint &operator*=(const modint rhs) noexcept {
    a = a * rhs.a % Modulus;
    return *this;
  }
  constexpr modint &operator/=(modint rhs) noexcept {
    u64 exp = Modulus - 2;
    while (exp) {
      if (exp % 2) {
        *this *= rhs;
      }
      rhs *= rhs;
      exp /= 2;
    }
    return *this;
  }
};
using mint = modint<mod>;
using vm = vector<mint>;
using vvm = vector<vm>;

ostream& operator << (ostream& os, const mint v){
os << v.value(); return os;
}

template <class T, class U> constexpr T power(T x, U exp) {
  T ret = static_cast<T>(1);
  while (exp) {
    if (exp % static_cast<U>(2) == static_cast<U>(1))
      ret *= x;
    exp /= static_cast<U>(2);
    x *= x;
  }
  return ::std::move(ret);
}

double calculate_objective_log(vector<int> &x, vector<int> &A){
    int N = A.size();
    double res = 0;
    vector<double> log_factoral(101010, 0);
    for(int i=1;i<101010;i++) log_factoral[i] = log_factoral[i-1] + log(i);
    for(int i=0;i<N;i++){
        res += x[i] * log(A[i]) - log_factoral[x[i]];
    }
    return res;
}

mint calculate_objective_mod(vector<int> &x, vector<int> &A, int K){
    int N = A.size();

    int A_sum = 0;
    for(int i=0;i<N;i++) A_sum += A[i];

    mint res = 1;
    for(int i=1;i<=K;i++) res *= i;
    for(int i=0;i<N;i++){
        for(int j=1;j<=x[i];j++) res /= j;
    }

    for(int i=0;i<N;i++){
        mint y = A[i];
        y /= A_sum;
        for(int j=1;j<=x[i];j++) res *= y;
    }
    
    return res;
}

void solve(){

    int N, K;
    cin >> N >> K;
    vector<int> A(N);
    for(int i=0;i<N;i++) cin >> A[i];
    int A_sum = 0;
    for(int i=0;i<N;i++) A_sum += A[i];

    vector<int> x(N, 0);
    vector<double> q(N, 0);
    int x_sum = 0;
    REP(i, N){
        x[i] = K * A[i] / A_sum;
        q[i] = (double) K * A[i] / A_sum;
        x_sum += x[i];
    }

    // dump(x)
    // dump(q)

    int nokori = K - x_sum;
    vector<pll> r;
    for(int i=0;i<N;i++){
        r.emplace_back(q[i]/(x[i]+1), i);
    }
    sort(r.rbegin(), r.rend());
    for(int i=0;i<nokori;i++){
        x[r[i].second]++;
    }

    // dump(x)
    // dump(calculate_objective_log(x, A));
    mint res = calculate_objective_mod(x, A, K);

    cout << res << endl;

    return;
}

int main(){
    int T;
    cin >> T;
    while(T--){
        solve();
    }
}